Automotive powertrains generally employ a transmission and a differential mechanism. The differential mechanism is included to permit distribution of power from the transmission to the drive wheels of a vehicle or to the fore and aft drive differentials of a vehicle. The differential mechanism commonly has an input gear member which rotates a housing or casing, a plurality of side gears, one of which is connected to drive a right axle and another of which is connected to drive a left axle.
The differential components for the most part rotate in unison with the rotation of the input gear. However, during some maneuvers, one axle may rotate more rapidly than the other. For example, if the vehicle is cornering, the outside wheel and axle and therefore the side gear of the differential rotate at a higher speed than the radially inner side gear of the differential. Also, when one axle is on a very slippery surface, such as snow or ice, that tire or wheel may rotate faster than the opposite tire or wheel that is on dry or good traction pavement. While the rotational difference during vehicle cornering is acceptable the rotation of one axle relative to the other resulting from slippage is not a desirable feature.
Many prior art differentials have included an internally operable clutch, which when sensing a speed differential between the two side gears is engaged to connect the two side gears together or to connect one side gear with the differential casing. In either event, the application of the clutch will cause unitary rotation of the differential device. That is, the casing and the side gears will rotate as a unit within the transmission differential.